Descriptions of suspicious incidents

How a Transportation Security Administration intelligence bulletin distributed to airport screeners July 20 described four suspicious incidents that gave rise to the warning:

_San Diego, July 7. A U.S. person _ either a citizen or a foreigner legally here _ checked baggage containing two ice packs covered in duct tape. The ice packs had clay inside them rather than the normal blue gel.

_Milwaukee, June 4. A U.S. person's carryon baggage contained wire coil wrapped around a possible initiator, an electrical switch, batteries, three tubes and two blocks of cheese. The bulletin said block cheese has a consistency similar to some explosives.

_Houston, Nov. 8, 2006. A U.S. person's checked baggage contained a plastic bag with a 9-volt battery, wires, a block of brown clay-like minerals and pipes.